380 THE THRUSH FAMILY 



studded in mud. When the wood cannot be found, which is likely 

 to occur fairly often, other material is perforce used. 



To account for the partiality for decayed wood shown by this 

 species is still more difficult. Wood is certainly not a necessary 

 constituent of a good plaster, for the mud linings of the other Thrushes, 

 or of the song-thrush itself, when it omits the wood, are just as 

 efficient for their purpose. One fails to imagine by what process the 

 instinct could have arisen which impels a song-thrush, building its 

 nest for the first time, to go about deliberately seeking for a material 

 so unusual. 1 Nor is it clear what it gains or loses by not adding the 

 inner grass lining of its congeners. A layer of grass has at least 

 the advantage of making it unnecessary for the bird to wait for 

 the plaster to dry, if in a hurry to lay its eggs. Eggs laid on wet 

 plaster are liable to adhere to it and get broken when moved either 

 accidentally or intentionally by the bird's feet. Let us add that 

 the very solidity of the lining has its dangers. After a heavy rainfall 

 nests have been seen more than half full of water, and Lord Lilford 

 found one with four eggs in it afloat. But this danger is incurred 

 also by blackbirds, whose young have been discovered dead in a nest 

 nearly half full of water. 2 



Blackbirds, thrushes and mistle-thrushes will rear more than one 

 brood in the same nest. Several instances have been recorded, among 

 them one by Lord Lilford in the work just quoted, who gives the case 

 of a thrush's nest in which two broods were reared. Nor was this all, 

 for the same nest was subsequently converted into a winter residence 

 by dormice. 3 A case of three broods being reared from one and 

 the same blackbird's nest is recorded by Dr. Hennicke in Naumann's 

 Vogel Mitteleuropas. Another instance is recorded in the Field, 

 June 15, 1901. A hen of the same species has been observed repair- 

 ing, on June 7, a nest which the first brood had left about May 28. 



1 For the evidence that the choice of nesting material is instinctive, see Professor Lloyd 

 Morgan's Habit and Instinct. 



2 Lilford, Birds of Northants, 1. 



3 For the mistle-thrush rearing two broods in the same nest, see the Zoologist, 1885, p. 335 ; 

 and 1877, p. 156 (two cases). Another case was noted by Mr. F. C. R. Jourdain (MI. litt.). 



